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Rf simulation Comsol 4.2

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Dear friends,
I'm simulating a 2D problem. (Electromagnetic waves)
I have a rectangle (2x10cm) of a lossy material inside an other bigger of air (7x15cm).
A plane wave, z polarized, comes from left (x<0) and hits the objects.
A perfectly matched layers of 1 cm are around the objects.
The frequency in 2.45GHz.
After the simulation run I can see the shape of the electric field.

THE PROBLEM
If I change the air rectangle dimensions, I see an other shape of electric field.
Why? The field distribution in the lossy material must be indipendent from the space around it. Or not?
Is the PML too thin?

Ciao at all

Ale

6 Replies Last Post Dec 19, 2011, 3:10 p.m. EST

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Posted: 1 decade ago Dec 16, 2011, 3:38 a.m. EST
Hi,

your rectangles and airbioxes size is close to the wavelength you investigate. So changing its size will of course change the field. I think your PML is much too thin and your air box is too small.

Cheers
Edgar
Hi, your rectangles and airbioxes size is close to the wavelength you investigate. So changing its size will of course change the field. I think your PML is much too thin and your air box is too small. Cheers Edgar

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Posted: 1 decade ago Dec 16, 2011, 5:13 a.m. EST
Thank you Edgar.
In the while I've made several simulation changing air and PML sizes without improvements.
The solution, so least I think, was the doubling the PML number of elements (from 5 to 10).
I hope to be in the right.
Thank you a lot.

What do you think about?

Bye Ale
Thank you Edgar. In the while I've made several simulation changing air and PML sizes without improvements. The solution, so least I think, was the doubling the PML number of elements (from 5 to 10). I hope to be in the right. Thank you a lot. What do you think about? Bye Ale

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Posted: 1 decade ago Dec 16, 2011, 2:52 p.m. EST
I'd do two things:
1. Increase the size of PML to 1 wavelength (12 cm). 5 elements are usually enough for PML.
2. Increase size of air domain around your box to 1.5 wavelength. Mesh 5 elements per wavelength.
I'd do two things: 1. Increase the size of PML to 1 wavelength (12 cm). 5 elements are usually enough for PML. 2. Increase size of air domain around your box to 1.5 wavelength. Mesh 5 elements per wavelength.

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Posted: 1 decade ago Dec 18, 2011, 4:05 a.m. EST
Thank you Alexander,
as soon as possible I'll try your's guidelines.

Ciao, Ale
Thank you Alexander, as soon as possible I'll try your's guidelines. Ciao, Ale

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Posted: 1 decade ago Dec 19, 2011, 1:54 a.m. EST
Dear friends,
what do you think about the same simulation in 3D: the rectangle becomes a box and the plane wave becomes five from arbitrary directions.

P.S. Do you think it is possible with a 32bit machine with 1 Gb of RAM?

Thank you,
Ale
Dear friends, what do you think about the same simulation in 3D: the rectangle becomes a box and the plane wave becomes five from arbitrary directions. P.S. Do you think it is possible with a 32bit machine with 1 Gb of RAM? Thank you, Ale

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Posted: 1 decade ago Dec 19, 2011, 3:10 p.m. EST
Ale,

see this youtube video for a step by step tutorial of a very similar study:

www.youtube.com/watch?v=fXm1GKXDXM0&feature=results_main&playnext=1&list=PL2629F619294AEFE9

cheers,
Felipe.
Ale, see this youtube video for a step by step tutorial of a very similar study: http://www.youtube.com/watch?v=fXm1GKXDXM0&feature=results_main&playnext=1&list=PL2629F619294AEFE9 cheers, Felipe.

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